Blister packs are of course well known for the storage and dispensing of pills, tablets and capsules, which are stored individually in cavities in a multi-cavity tray and removed by pushing each pill, tablet or capsule through a rupturable film or foil covering the cavities. The film or foil cover may be paper or a plastics film that can be peeled or torn away to expose the medication in the tray cavities, but is generally aluminium foil, which has the dual advantage of being easily rupturable and vapour-impermeable. Such blister packs normally carry only one unit dose of the same medication in each cavity.
Mixed medication blister packs have been proposed, having larger cavities for filling by a pharmacist, wherein each cavity in a multi-cavity tray can be filled with a mixture of medications. Typically, a tray may have a 2×7, 3×7, 4×7 or 5×7 array of cavities corresponding to 2, 3, 4 or 5 predefined medication times per day over a 7-day period, or one dose prescribed per day over a 2, 3, 4 or 5 week period. For example, a 4×7 tray may be filled with the medication to be taken at breakfast-time, lunchtime, early evening and immediately before retiring each day for a week, and then the filled cavities sealed with a rupturable or sequentially rupturable film or foil cover. Printed instructions on the pack identify the intended sequence of opening the individual cavities to dispense their contents according to the prescribed dosage regimen.
Disadvantages of conventional blister packs using a rupturable cover sheet are the difficulty experienced by some patients, particularly the elderly, in pushing the medication through the cover sheet, the need for expensive laminating equipment to seal the aluminium cover sheet over the cavities after the initial filling, and the difficulty experienced by the user in selecting the cavity containing the medication to be dispensed if the medication is pushed up through the foil from below. If the wrong cavity is opened by mistake then re-sealing is impossible because the cover sheet has ruptured.
A major disadvantage of the blister pack using a peelable cover sheet is the difficulty experienced by the user in peeling or tearing away a single selected portion of the cover sheet to expose the contents of only one preselected cavity. This can be achieved by scraping a finger-nail over a corner or tab portion of a segment of the cover sheet sealing the preselected cavity, but grasping that corner to peel away the complete segment sometimes requires considerable manual dexterity and possibly good eyesight, which is beyond the abilities of many elderly users. Also, if a tacky peelable adhesive is used to adhere the cover sheet to the tray, it is desirable to prevent the contents of the tray from coming into contact with the adhesive. Finally, the film cover sheet may not have as high a vapour impermeability as metal foil, so there is a reluctance on the part of pharmacists to pre-fill a mixed medication blister pack with medication for administration more than seven days in advance of the filling date, lest the medication deteriorates due to storage in humid ambient conditions.
WO 2005/023670 to the present Applicant describes a container that aims to overcome some or all of the above problems and disadvantages. The container is for storing and dispensing consumer products and includes a tray having a generally planar top surface into which has been formed one or more discrete cavities for receiving the consumer products. A cover film is adhered to the generally planar top surface of the tray by a layer of peelable adhesive to seal the one or more cavities to retain the consumer products in the one or more cavities. The cover film has pre-formed tear lines defining a tear-off portion per cavity to retain the consumer products in that cavity until it is removed by tearing along its tear lines. In practice it will be readily appreciated that the or each tear-off portion can also be defined by cut lines extending completely through the material of the cover film. The or each tear-off portion of the cover film has low vapour transmission properties in the area which in use overlies the associated cavity, those low vapour transmission properties being created by a barrier patch with high vapour barrier properties shaped and sized to overlie the associated cavity. The or each barrier patch is adhered to the underside of the cover film by the same layer of peelable adhesive as that which adheres the cover film to the top surface of the tray.
The barrier patch beneath the or each tear-off portion can be created from a single sheet of barrier film as follows. A single sheet of barrier film is secured to the underside of the cover film by a peelable adhesive. The barrier film has pre-formed tear-lines defining the periphery of the or each vapour-resistant barrier patch so that peeling away the majority of the barrier film from the cover film immediately prior to application of the cover film to secure it to the generally planar top surface of the tray exposes the peelable adhesive in areas necessary for adhesion to the tray but leaves a barrier patch attached to the underside of the or each tear-off portion of the cover film. In practice it will be readily appreciated that the or each barrier patch can also be defined by cut lines extending completely through the material of the barrier film.
The sheet of barrier film can have a further pre-defined tear line (or cut line) close to one edge thereof to define a tear-off strip which when removed exposes a location anchorage area of the peelable adhesive on the underside of the cover film, for adhering an edge portion of the cover film to an edge portion of the tray before peeling away the majority of the barrier film and adhering it over the cavities. To assist in the process of adhering the cover film to the top surface of the tray, the tray can have upstanding cover film location means. The cover film can have cooperating means for accurate location of the cover sheet over the tray with the one or more cavities and associated tear-off portions in register before adhering the cover film to the tray.
A similar container is described in EP 1357050 to the present Applicant but in this case each tear-off portion of the cover film includes a lug portion that overlies the generally planar top surface of the tray and which can be readily grasped by the user. The top surface of the tray includes upwardly extending protrusions that are located beneath the or each lug portion in use to bend that lug portion upwardly out of the plane of the remainder of the cover film.
It will be readily appreciated that WO 2005/023670 and EP 1357050 describe a “cold seal” process where the cover film is secured to the tray by the same layer of peelable adhesive that is used to secure the cover film to the barrier film.
After the majority of the barrier film has been peeled away from the cover film to expose the peelable adhesive, the cover film can be secured manually to the top surface of the tray. The cover film can also be secured to the tray using an industrial “cold seal” process. A typical process might involve securing the cover film to the tray using a high-speed, on-line sealing apparatus. This will normally require the laminated seals (i.e. the combination of the cover film and barrier film) to be supplied as a continuous reel and the automatic application of the cover film to the tray requires the surplus barrier film to be removed during the sealing process. The barrier film therefore has to be wound onto a waste cylinder or placed in a waste container before being recycled. In the case of the seals described in EP 1357050 the action of securing the cover film to the tray causes the lug portions to be bent upwardly out of the plane of the remainder of the cover film by the upwardly extending protrusions. This can be difficult to implement properly using an industrial “cold seal” process.